This disclosure is related to the field of micro-fluidic devices. In particular, the disclosure is related to capillary flow micro-fluidic devices or lateral flow micro-fluidic devices.
Capillary flow devices can be used to detect the presence or the absence of an analyte in a fluid sample. An advantage of these devices is that no external pumps or valves are necessary to pump the fluid through the device. Inside these capillary flow devices, a capillary action is created to ensure that the fluid flows through the device.
In state of the art capillary flow devices, a fluid propagates through the device in one direction. Also, in state of the art capillary flow devices, a fluid can only propagate continuously through the device, e.g., it cannot be stopped. This is a disadvantage as this limits the functionality of the device for liquid manipulation that makes these devices only suitable for “one-step” bio-assays. The unidirectional fluid movement highly limits the application of these devices, as most of the bioassays require multiple steps whereby, for example, first, a binding with the analyte takes place and, second, a detection is performed. Another disadvantage is the flow resistance a fluid experiences inside state of the art capillary flow devices. When the fluid propagates through the device, the fluid movement tends to slow down and eventually stop as the flow resistance increases along the channel of the device.
There is a desire for capillary flow devices that overcome one or more disadvantages of the prior art, in particular, in which the propagation of the fluid through the capillary flow device can be more precisely controlled.